Rotary crank-driven intermittent grip



Dec. 26, 1950 F. A. GRUETJEN 2,535,913

ROTARY CRANK DRIVEN INTERMITTENT GRIP Filed Aug. 24, 1946 s Sheets-Sheet 1 INVENTOR.

fifd rlcnx $247212 Dec. 26, 1950 F. A. GRUETJEN 2,5359918 ROTARY CRANK DRIVEN INTERMITTENT GRIP 3 Sheets-Sheet 2 Filed Aug. 24, 1946 /5 22 in 23 u 7 I gin/1 IN VEN TOR.

Patented Dec. 26, 1950 UNITED STATES PATENT OFFICE Frederick A. Gruetjen, Milwaukee, Wis., assignor to A. 0. Smith Corporation, Milwaukee, Wis., a

corporation of New York Application August 24, 1946, Serial No. 692,767

Claims.

This invention relates to a stoker drive and has particular reference to the employment of a pinch clutch for intermittently driving the feed screw of a stoker.

The principal object of the invention is to provide an efiicient and durable intermittent drive for a stoker that is inexpensive to construct and assemble.

Another object is to provide a subtsantially quiet drive for a stoker feed screw.

Another object is to provide a novel shear pin assembly for a stoker drive.

These and other objects of the invention will appear hereinafter in connection with the following description of an embodiment of the invention illustrated in the accompanying drawings.

Figure 1 is a side elevational view of the drive of the invention with the unit at the beginning of the driving stroke;

Fig. 2 is a similar view with the unit at the end of the driving stroke;

Fig. 3 is a top plan view of the driving unit;

Fig. 4 is a section taken on line i-4 of Fig. 3;

Fig. 5 is an elevational view of the driving drum;

Fig. 6 is a section through the drum taken on line 6-6 of Fig. 5; and

Fig. 7 is a detail section taken on line 1-4 of Figure 1.

The drawings illustrating an embodiment of the invention show a base plate i of a coal stoker unit to the inner end of which is secured a hopper 2 with a wall which extends vertically upward from base I and then turns diagonally outwardly over the base. Side walls, not shown, are secured to the hopper and to base I to house the driving unit of the stoker.

The bearing plate 3 is bolted to the vertically extending wall of hopper 2 directly above base I and receives the housing 4 of the clutch shaft 5 which extends horizontall therethrough within the bushing 6.

The inner end of shaft 5 is locked to the feed screw, not shown, to drive the same. Shaft 5 is driven from the motor and transmission assembly 1 through the connecting rod 8 and the pinch clutch drive of the invention. The motor and transmission assembly are suitably secured to base I at the left side thereof as viewed from Figure 1.

The pinch clutch drive has a sheet metal drum 9 which is secured to the rear end portion of clutch. shaft 5 between plates ID by the nut H. The forward plate ID abuts against the rear end or shaft-housing 4.

Drum 9 is formed of two half members I2 which when interlocked together provide a square central opening [3 for locking the drum in shaft 5 which is squared at the rear end complementary to the drum opening. When nut H is tightened the drum is held against axial movement between plates in and by housing 4.

The circumferential wall of drum 9 is provided with circumferential slot l4 which extends completely around the drum when half members 42 are assembled together.

The lower end of the lever arm l5 projects into slot I l a substantial distance and is connected to the drum by pin [6 which extends transversely across slot M on the outside of the wall of drum 9 and by pin ll which extends transversely across slot I 4 on the inside of the peripheral wall of the drum. The pins i5 and I l engage opposite sides of the wall of drum 9 with pin is set slightly ahead of pin I! in the direction of movement of drum 9 for eflective engagement of the drum to drive the same.

The outer pin it is held in place by clips l8 to permit ready replacement in the event of shearing in service while the inner pin 11 is press fitted in place through suitable apertures in drum 9.

The upper end of lever arm I 5 is pivoted to the upper end of connecting rod 8 for actuation by rod 8 when the latter is reciprocated by motor and transmis ion assembly 1, as will be described.

A spring I9 is attached at one end to lever arm [5 preferably to the right of the inner pivot pin l1 and the other end of the spring is connected to bracket 2!] which is secured to hopper 2. Spring I9 biases arm I 5 in an upwardly direc tion tending to pull the arm opposite the rotational direction of drum 9.

The adjustable end 2! of the stroke regulating bracket 22 which is suitably secured at the outer end to the frame, supporting hopper 2, extends diagonally within slot l4 and engages inner pin [1 to interrupt the rotary movement of drum 9 by preventing further movement of arm. 15 in a clockwise direction. By adjusting end 2! inwardly or outwardly the rotary movement of drum 9 may be decreased or increased by enabling arm l5 to move in a lesser or greater clockwise movement as the case may be.

Figures 1 and 2 illustrate, respectively, the clutch assembly at the beginning of the driving stroke and after completion of the same.

As shown in Figure 1, when connecting rod 8 is reciprocated upwardly by motor and trans mission 1, lever'arm l5 isrotated by rod 8 in a' clockwise direction. This movement of arm l5 moves the line of centers of pins l6 and I! to substantially right angles to the circumferential wall of the drum 9 and disengages the pins from the drum wall. At the same time spring 19 pulls the lower end portion of lever arm [5 in a clockwise direction with a slight lag behind the rotary movement given the arm by rod 8, and the pins I6 and 11 carrying arm l5 in slot l4 ride freely over the circumferential wall of the drum. The clockwise movement of arm l5 continues until inner pin ll engages end 21 of bracket 22.

When rod 8 is reciprocated downwardly by motor and transmission 1, arm 8 immediately rocks to a position where the peripheral wall of the drum is clamped between pins l6 and l! as spring i9 tends to pull the lower end of arm IE to the right. As arm l5 moves downwardly drum 9 is rotated in a counter-clockwise direction until the end of the stroke is reached and arm l5 is again pushed upwardly by rod 8. The rotation of drum 9 in a counter-clockwise direction continues intermittently as pins l6 and I1 clamp the drum wall in moving in a counter-clockwise direction and ride freely over the drum upon L moving in a clockwise direction.

As drum 9 rotates, shaft 5 is rotated and intermittently drives the feed screw, feeding coal to the furnace from hopper 2.

In order to insure that there will be no reverse rotation of drum 9 when arm I5 is pushed upwardly and pins l5 and il ride freely along the drum, a second lever arm 23 is pivoted at one end to bracket 24 on base I of the stoker unit and the other end projects a substantial distance within slot M.

A pin 25 simi ar to pin 5'! of arm it? extends transversely across slot M on the inside of the peripheral wall of drum 9 and the pin 26 similarly to pin 16 of arm 15 extends transversely across slot M on the outside of the drum wall.

Pins 25 and 26 are offset but whereas outer pin I6 is offset to the left of the center line of arm I5, the outer pin 26 of arm 23 is offset to the right of the center line. Pin 25 is offset to the left of the center line of arm 23 whereas pin 1Ii! of arm 55 is offset to the right of the center By offsetting pins 25 and 26 as described, when drum 9 is rotated from motor and transmission 1 through rod 8 and arm IS in a counterclockwise direction, pins 25 and 26 ride freely over the peripheral wall of the drum. However, at the end of the driving stroke pins 25and 2E clamp the drum wall therebetween so that when the driving arm l5 and pins I 6 and i? move to the right drum 9 cannot rotate to the right with them in a clockwise direction. Shaft 5 remains stationary as does the feed screw.

The invention provides an inexpensive drive for a stoker that drives the feed screw intermittently with substantially silent operation.

The drum 9 is readily formed from two half members and keyed to shaft 5 as described. The inner pins ll and 25 are readily inserted into their respective arms by openings provided in the sides of the drum 9 at locations suitable-for locating the pins and arms.

The pin I8 of the driving unit and the pin 26 of the holding unit are readily replaceable in the event thatv they shear in service, which is important from the operators standpoint.

Various embodiments of the invention may be employed within thescope of the accompanying claims-:4

lever arm secured at one end to said reciprocating element and having the other end disposed to grip the wall of said tubular member to rotate the same when the arm is moved in one direction and to disengage said member and ride free of the same Whensaid arm is moved in the opposite direction, and a second lever arm anchored at one end to the frame of the stoker assembly with which the clutch is employed and extending within the slot in said tubular element, a pin extendin transversely through said lever arm on the inside of said tubular element, and a second pin extending transversely through said arm on the outside of said tubular element with said pins being offset to immediately grip said tubular element and prevent reverse rotation of the same when the end of the driving lever arm rides free of the drum and to ride freely over the tubular member when the same is being driven.

.2. A pinch clutch stoker drive for driving a shaft from a power source through a reciprocating connecting rod to intermittently rotate a stoker screw, which comprises a sheet metal drum secured to said shaft and having a circumferential slot extendin in the circumferential wall thereof, a lever arm secured at the upper end to said reciprocating rod and having the lower end extending into said drum through said slot, means at the lower end of said arm to engage the drum and rotate the same when the lever arm is rotated in one directionby said reciprocatof said arm in a direction opposite to the rotational direction of said drum, and an adjustable stop disposed to engage the lower end portion of said arm to limit the rotary movement of said drum to regulate the feed of said stoker screw.

3. A pinch clutch stoker drive for driving a shaft from a power source through a. reciprocating connecting rod to intermittently rotate a stoker screw, which comprises a sheet metal drum secured to said shaft and having a circumferential slot extending in. the circumferential wall thereof, a lever arm secured at the upper end to said reciprocating. rod and having the lower end thereof extending into said drum through the circumferential slot therein, a pair of pins connecting the lower end of the lever arm to said drum with the outer pin extending transversely through the arm on the outside of the circumferentially extending drum slot and the inner pin extending transversely through thearm on the inside of said. slot, and said outer pin. being offset from the inner pin in,

the drum and the other 'end secured to theframe of the stoker assembly to bias said arm in a direction opposite to the rotational direction of said drum.

4. A pinch clutch stoker drive for driving a shaft from a power source through a reciprocating connecting rod to intermittently rotate a stoker screw, which comprises a sheet metal drum secured to said shaft and having a circumferential slot extending in the circumferential wall thereof, a lever arm secured at one end to said reciprocating rod and having the other free end thereof extending into said drum through the circumferential slot therein, a pair of pins connecting the free end of the lever arm to said drum with one pin extending transversely through the arm on the outside of the circumferentially extending drum slot and the other pin extending transversely through the arm on the inside of said slot, and said pins being disposed to clamp the drum therebetween and rotate the latter when said rod is reciprocated in one direction and to disengage the drum and ride free of the same when said rod is rotated in the opposite direction, a spring secured to the lower end of the lever arm to bias the same in the direction of reciprocation of said rod when the pins ride free of the drum and an adjustable stop projecting through the slot in said drum and engaging the pin on the inside of the drum to limit the rotary movement of the drum and regulate the feed of said stoker screw.

5. A pinch clutch stoker drive for driving a shaft from a power source through a reciprocating connecting rod to intermittently r0- tate a stoker screw, which comprises a sheet metal drum secured to said shaft and having a circumferential slot extending in the circumferential wall thereof, a lever arm secured at one end to said reciprocating rod and having the other free end thereof extending into said drum through the circumferential slot therein, a pair of pins connecting the free end of the lever arm to said drum with one pin extending transversely through the arm on the outside of the circumferentially extending drum slot and the other pin extending transversely through the arm on the inside of said slot, and said pins being disposed to clamp the drum therebetween and rotate the latter when said rod is reciprocated in one direction and to disengage the drum and ride free of the same when said rod is reciprocated in the opposite direction, a spring secured to the lower end of the lever arm to bias the same in the direction of reciprocation of said rod when the pins ride free of the drum, a second lever arm anchored to the stoker frame at one end and extending into said slot substantially opposite the first mentioned lever arm and; connected to said drum by pins extending across said slot on the inside and outside of said drum, said pins being disposed to clamp the drum and prevent rotation thereof when the pins of the first mentioned lever arm ride freely over the drum and to disengage the drum and ride free of the same when the pins of the first mentioned lever arm clamp the drum and rotate the same.

FREDERICK A. GRUETJEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 231,843 Onderdonk Aug. 31, 1880 289,335 Byrkett Nov. 27, 1883 451,476 Gawley May 5, 1891 1,190,704 Barton July 11, 1916 2,123,724 Grisdale July 12, 1936 FOREIGN PATENTS Number Country Date 324,968 Great Britain Feb. 5, 1930 

